Lemma 2.1 ([1]})
The power functions \(p_{k}(x)=x^k\)  and \(p_{l}(x)=x^l\)  on \(\mathbb {F}_{p^n}\)  are CCZ equivalent, if and only if
there exists a positive integer \(0\le a < n\) , such that \(l\equiv p^a k~({\rm mod}\ p^n-1)\)  or \(kl\equiv p^a~({\rm mod}\ p^n-1)\) .

